Negative Bias Temperature Instability And Charge Trapping Effects On Analog And Digital Circuit Reliability

Nanoscale p-channel transistors under negative gate bias at an elevated temperature show threshold voltage degradation after a short period of stress time. In addition, nanoscale (45 nm) n-channel transistors using high-k (HfO2) dielectrics to reduce gate leakage power for advanced microprocessors exhibit fast transient charge trapping effect leading to threshold voltage instability and mobility reduction. A simulation methodology to quantify the circuit level degradation subjected to negative bias temperature instability (NBTI) and fast transient charge trapping effect has been developed in this thesis work. Different current mirror and two-stage operation amplifier structures are studied to evaluate the impact of NBTI on CMOS analog circuit performances for nanoscale applications. Fundamental digital circuit such as an eleven-stage ring oscillator has also been evaluated to examine the fast transient charge transient effect of HfO2 high-k transistors on the propagation delay of ring oscillator performance. The preliminary results show that the negative bias temperature instability reduces the bandwidth of CMOS operating amplifiers, but increases the amplifier\u27s voltage gain at mid-frequency range. The transient charge trapping effect increases the propagation delay of ring oscillator. The evaluation methodology developed in this thesis could be extended to study other CMOS device and circuit reliability issues subjected to electrical and temperature stresses

Bohmian mechanics, the quantum-classical correspondence and the classical limit: the case of the square billiard

Square billiards are quantum systems complying with the dynamical quantum-classical correspondence. Hence an initially localized wavefunction launched along a classical periodic orbit evolves along that orbit, the spreading of the quantum amplitude being controlled by the spread of the corresponding classical statistical distribution. We investigate wavepacket dynamics and compute the corresponding de Broglie-Bohm trajectories in the quantum square billiard. We also determine the trajectories and statistical distribution dynamics for the equivalent classical billiard. Individual Bohmian trajectories follow the streamlines of the probability flow and are generically non-classical. This can also hold even for short times, when the wavepacket is still localized along a classical trajectory. This generic feature of Bohmian trajectories is expected to hold in the classical limit. We further argue that in this context decoherence cannot constitute a viable solution in order to recover classicality.Comment: Figures downgraded to low resolution; To be published in Found. Phys. (2009)

Infrared imaging camera based on a Rydberg atom photodetector

A type of infrared imaging camera is demonstrated that uses gas-phase Rydberg atoms as photocathodes. The camera operates throughout the infrared part of the electromagnetic spectrum: l51 – 100 mm. The first results are presented and the potential of the camera as an ultrafast detector and a wavelength selective detector is discussed

Asymmetry in the strong-field ionization of Rydberg atoms by few-cycle pulses

Contains fulltext : 60146.pdf (publisher's version ) (Open Access)We present measurements of the electron ejection direction in the ionization of high (n=90) Rydberg states of rubidium subjected to few-cycle radio-frequency (RF) pulses. For weak pulses we find a strong asymmetry for even (cosine) pulses and no asymmetry for odd (sine) pulses. This asymmetry disappears for pulses longer than four RF cycles. For strong pulses, very large asymmetry is found for both sine and cosine pulses that persists up to eight RF cycles and is attributed to initial state depletion effects within a cycle

Demonstration of a Far Infrared Streak Camera.

An atomic infrared (IR) streak camera is demonstrated that operates in the mid- and far-infrared (λ = 5-85 μm), well beyond the long wavelength cutoff of conventional streak cameras. The temporal and spectral characteristics of the streak camera are determined using the FELIX free-electron laser as the IR light source. The temporal resolution of the streak camera was found to be as short as 1.2 ps. The high sensitivity of the streak camera is demonstrated by single-shot characterization of the IR pulses of FELIX